Andy Murray in the semis

Brisbane: With an infected big toe and a lopsided losing record against Serena Williams, top-ranked Victoria Azarenka decided it was safest to withdraw from the Brisbane International semi-finals rather than risk aggravating the injury so close to her Australian Open title defence.

Azarenka made the announcement Friday about a half hour before she was due to play No. 3 Serena, who is on a roll after winning titles at Wimbledon, the London Olympics and the US Open.

Andy Murray, the Olympic gold medallist and US Open champion, finished off his 6-4, 7-6 (3) win over Uzbekistan’s Denis Istomin in the quarter finals. Murray had lapses in his opening three-set win over No. 199-ranked Australian qualifier John Millman on Thursday night, while Ivan Lendl was en route to Australia, but had no serious trouble with his coach in the stands.

The first of Murray’s three titles in a breakthrough 2012 season was in Brisbane, where he started working with former No. 1-ranked Lendl last January. The next two titles were career-defining triumphs at the London Olympics and US Open.

Murray said he was satisfied with his serve — he didn’t get broken in the match — and was starting to get over the aches and pains that are usual when returning from the end-of-season break.

“When you’re practicing it’s hard to replicate match situations... and they’re the things that take a while to get back into the rhythm of playing,” he said, putting his relatively slow start in Brisbane down to a lack of match practice rather than a lack of condition and rejecting the suggestion he had been “rusty”.